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Collaboration and Licensing Agreements - Additional Information (Detail) $ / shares in Units, $ in Thousands		3 Months Ended
	May 17, 2018 USD ($) item $ / shares shares	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue from contract with customer		$ 8,093	$ 4,382
Clinical Compound Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue from contract with customer		$ 72	140
Vifor Fresenius Medical Care Renal Pharma Ltd. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-refundable, non-creditable upfront payment	$ 50,000
Common stock, shares issued \| shares	1,174,827
Purchase of common stock value	$ 20,000
Purchase common stock per share amount \| $ / shares	$ 17.024
Closing prices of company common stock description	over a pre-determined average closing price of the Company’s common stock
Premium from sale of stock	$ 5,444
Contract liabilities	$ 55,444
Number of combined performance obligations for revenue recognized \| item	1
Number of days to terminate agreement		60 days
Termination notice effective period		12 months
Vifor Fresenius Medical Care Renal Pharma Ltd. [Member] \| Maximum [Member] \| Regulatory and Commercial Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments receivable	$ 470,000
Vifor Fresenius Medical Care Renal Pharma Ltd. [Member] \| Maximum [Member] \| Regulatory Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments receivable	30,000
Vifor Fresenius Medical Care Renal Pharma Ltd. [Member] \| Maximum [Member] \| Tiered Commercial Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments receivable	$ 440,000
Maruishi Pharmaceutical Co., Ltd. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Cost of clinical compound related to R&D expense		$ 65	126
Maruishi Pharmaceutical Co., Ltd. [Member] \| Clinical Compound Revenue [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue from contract with customer		$ 72	$ 140